Wire guides are frequently used to position medical devices, such as balloon catheters, at a desired location in a patient's body (e.g., the vascular system). In a typical procedure, a wire guide is first inserted into a body lumen and steered into position followed by advancing a balloon catheter over the wire guide to the desired treatment site.
Typical balloon catheters are composed of an elongated shaft with an inflatable balloon portion attached to the distal end of the elongated shaft. The shaft typically has multiple lumens, one being an inflation lumen for the balloon and another serving as a wire guide lumen to allow the catheter and shaft to be advanced over a wire guide that has already been positioned in a patient. The elongated shaft of one type of typical balloon catheter terminates just inside the proximal end of the balloon, where a second, smaller single lumen shaft/cannula is bonded onto the main shaft and extends through the interior of the balloon in order to preserve the wire guide lumen through to the distal end of the balloon. The presence of the smaller shaft within the balloon allows the balloon to initially be mounted on the proximal end of the wire guide and advanced over the wire guide without the wire guide poking and damaging the balloon material.
The smaller wire guide shaft within the balloon may be about 0.050″ in outer diameter in order to accommodate a wire guide of about 0.035″ outer diameter. The presence of the smaller shaft in the interior of the balloon, however, adds to the overall dimensions of the balloon, thus limiting the use of the balloon catheter in applications requiring a still lower profile balloon. Thus, there exists a need for lower profile balloons and systems for advancing lower profile balloons onto wire guides that have already been positioned in a patient.